Natural Repellant?

Junior Guinea Pig

Hi all!
A week or so ago I posted a thread (A Threat to Health?) about how some cockroaches were in my piggies' run. It has gotten a bit colder now so I thought they'd go away but they're still there. I was reading an article about natural roach repellents (A brief overview of natural cockroach repellents) and It mentions these things:

Tea tree oil
Tea tree oil is very effective against cockroaches. Mix quarter cup tea tree oil and quarter cup vinegar with two cups of water. Spray the mixture in and around the infested locations.Lemon
Lemon is used for many culinary and non culinary purposes. Cut lemon into wedges. Place them in a small container. Place the container in the infested location. Cockroaches are repelled by the aroma of lemon.